ODVA reported Nov. 12 that its Common Industrial Protocol (CIP) for Safety on EtherNet/IP has been enhanced to allow using its CIP Concurrent Connections for applications requiring high availability and functional safety. Concurrent Connections allow communication redundancy between multiple producing and consuming devices for critical automation processes. CIP Safety provides failsafe communication between nodes, such as safety I/O blocks, safety interlock switches, safety light curtains and safety controllers in machine and process automation safety applications up to Safety Integrity Level (SIL) 3 according to IEC 61508 standards. Employing Concurrent Connections with CIP Safety on EtherNet/IP allows redundancy and functional safety to be integrated to ensure the best uptime and worker safety.
Concurrent Connections are CIP connections that support fault tolerance via redundant devices. Concurrent Connections enable many CIP connection paths, which allow data to be sent multiple times over multiple paths between producing and consuming devices—independent of how the devices are physically connected. Originators, routers and targets can all have multiple devices participating, and the Concurrent Connection and any of the duplicated device pairs can fulfill the role and the connection. This reduces time that would otherwise be needed to detect failures, and eliminates time that would have to be spent switching between paired devices. The redundant pair send and receive data continuously, so even if a failure is detected in one of the devices, the control process can continue uninterrupted.
“The availability of Concurrent Connections for CIP Safety on EtherNet/IP creates a new level of assurance that industrial networks will be resilient and safe in the face of device failure or communication errors,” says Dr. Al Beydoun, president and executive director at ODVA. “Concurrent Connections for CIP Safety is a win-win that offers the highest availability and functional safety to enable the toughest applications to be handled, while reducing injuries and increasing output.”
ODVA adds that CIP Safety mitigates common errors that can result in hazardous situations via various techniques as described in IEC 61784-3-2. Time stamps are used with time expectation to detect if packets are lost, delayed, repeated or transmitted out of order. Unique device identifiers are used to authenticate communication between two safety devices. Added diagnostics and checks are included to validate that messages aren’t corrupted in transit, and these features are separate from standard communication methods. When these mitigations are put together as CIP Safety, a single connection between two wired or wireless devices can be used for communications certified up to SIL 3 per IEC 61508 and up to Category 4/PLe per ISO 13849-1.
CIP Safety and Concurrent Connections have been available separately to provide industrial network functional safety and redundancy in the case of device errors or failure. The purpose of Concurrent Connections for CIP Safety is to give automation network designers a way to leverage the higher system availability advantages offered by standard Concurrent Connections, while maintaining the safety integrity offered by CIP Safety connections. The latest version of the EtherNet/IP and CIP Safety specifications for details on Concurrent Connections for CIP Safety on EtherNet/IP are available at ODVA’s website.
